Study on material relative permittivity using TE011 cylindrical microwave cavity

In this paper a cavity resonator system based on microwave perturbation theory which is used for measuring the relative permittivity of material has been presented. The cavity works with the frequency of 7GHz and TE₀₁₁ is chosen as the working mode to avoid other perturbing modes. After calculating and analyzing rectangle waveguide WR-112 is chosen to feed energy for the cavity. The radii of coupling aperture and radii of capillary are optimized. Results show that aperture radius=4mm and capillary=2.6mm make the system perform better. Five different samples are filled in the capillary to verify the performance of the cavity and the cavity resonator is highly sensitive to the change of dielectric constant of materials and it can be used for characterizing and studying dielectric character of materials.